This invention relates to a device for mounting a flexible line on a structure, of the kind comprising:                a hollow rigid member, intended to be integral with the structure, the hollow rigid member defining a traveling way of the flexible line;        a curvature limiter defining an insertion lumen of the flexible line, with the insertion lumen having a travel axis of the flexible line, the curvature limiter being movable relative to the hollow rigid member between a position away from the hollow rigid member and a position mounted on the hollow rigid member;        releasable means for axial immobilization of the curvature limiter on the flexible line in at least one first direction along a travel axis, for moving the flexible line together with the curvature limiter relative to the hollow rigid member between the position away from the hollow rigid member and the mounted position.        
Such mounting devices are used in hydrocarbon exploitation installation on a body of water, including for instance a fixed rigid structure on the seabed, an oscillating structure secured to the seabed, or a floating structure, such as a surface naval base, a semisubmersible platform, a floating vertical column, or a vessel.
The flexible line to be mounted on the structure is for instance a flexible rising fluid carrying pipe, a so-called riser. Herein “flexible pipes” are understood to mean those described in the standards published by the American Petroleum Institute (API), API 17J and API RP 17 B, and well known to the person skilled in the art. More generally, the flexible line can be a bundle-like composite harness, a set of umbilicals or electrical cables.
A mounting device of the aforementioned type is used when installing and connecting the flexible line to the surface structure.
For this purpose, in order to reduce the risks of damaging the structure and the flexible line, it is known to immerse the flexible line into the body of water below the surface structure and to lift it up to the connecting area located on the surface structure by means of a hoist. Such a connection is referred to by the term pull-in.
The flexible line is guided over the structure by introducing the same through a hollow rigid tube integral with the structure and oriented vertically, which is a protective sleeve. The hollow tube is for instance of the “I tube” or “J tube” type.
At the upper outlet of the tube, the flexible line is connected to the surface installation.
In order to avoid any deterioration of the flexible line, namely under the effect of water agitation likely to bring it into contact with the structure, it is known to engagedly mount around the flexible line a curvature limiter adapted to locally impose a radius of curvature greater than the minimum radius of curvature which may be adopted by the flexible line.
Hereafter, curvature limiters are understood to both curvature limiters, composed e.g. of articulated rigid elements called “vertebrae”, and stiffeners, composed e.g. of plastic molded blocks, as well as combinations thereof.
A stiffener is for instance arranged around the flexible line close to the upper end thereof, so as to cooperate with the hollow tube when the flexible line is inserted into the tube.
For this purpose, first of all, the stiffener and the flexible line are moved together to the lower end of the hollow tube until the stiffener has been partially inserted into the hollow tube. Next, in a second stage, the flexible line is moved upward in relation to the stiffener for lifting the same up through the hollow tube in view of connecting it to the surface structure.
During this second phase, the stiffener is maintained to be translationally immobile within the hollow tube through embedding and/or fastening by means of hose clamps.
For these two steps to be performed successively, pulling systems are known using at least two different hoists. The cable of a first hoist is connected to the stiffener so as to be lifted up toward the lower end of the hollow tube, and the cable of a second hoist is connected to the upper end of the flexible line so as to move the same in relation to the stiffener. Such a system requires precise control of the lifting of the cables, and therefore is not easy to use, in particular if the hollow tube is bent.
In order to compensate for this problem, it is known from WO 98/23845 to use a single hoist for pulling the flexible line and the stiffener by temporarily integrating the stiffener with the flexible line by means of a frangible pin.
When the stiffener is lifted toward the lower end of the hollow tube, the stiffener and the flexible line will move together. Next, the stiffener is fastened to the lower end of the tube. Sufficient traction is then applied upward on the flexible line so as to break the frangible pin in order to allow for the flexible line to move upward in relation to the stiffener.
Such a device is not entirely satisfactory. In fact, such a device according to prior art is complex and requires mechanical parts to be highly reliable. Furthermore, once the frangible pin has broken, it is no longer possible to disconnect the line from the structure, then to reconnect it to the same structure or to another structure, without reinstalling a pin, which requires for the flexible line and the stiffener to be lifted up to the surface.